Peavey Windsor 120 Watt head schematic?

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Ya I know, but you can't find a tube half stack for that cheap form any other company.

I does have some room for improvement though. I don't know how it sounds in person but I have watch demo's of it on youtube and it does sound pretty good. The only issue I can see is it's hard to get clean tone out of it though. But some mods can fix that.

I've been wanting to experiment with this head. It would be a great bargain if you can get it to clean up, which I'm pretty sure it possible.

My goal is to lower the gain, possibly make it switchable, and then lower the output to 50w or less. Another option is to basically turn it into an JCM 800 since, from what I can tell, it's helluva close already.

Peavey Windsor schematic: Windsor SCHEMATIC.pdf

Marshall JCM 800 (2203 100w) schematic: JCM800_lead_mstvol_100w_2203 SCHEMATIC.pdf

I'm a definite newbie when it comes to electronics, but I work with a retired electrical engineer and old hi-fi equipment all the time, so I'm learning a lot.

Here's a suggestion from the engineer dude to possibly lower the gain:

Also, suggestions from another friend to make the preamp like JCM800:
Remove R14 - replace with Jumper
Remove R5 - replace with 820 ohm
Snip C28
Remove C18 - replace with Jumper
Remove R56 - replace with Jumper
Snip R70
Snip C41
Remove R65 - replace with Jumper
Remove C6 - replace with Jumper
Remove R21 - replace with 100K
Snip R36

All these should mean the pre-amp is like a JCM800 - apart from the low gain input needs fixing also. Will look into this.

I don't actually own the amp yet, but figured if I could lower the gain and power, it would be practical for me and would warrant a purchase.
Also, here are my GO-TO clips for anyone asking what the Windsor sounds like:

Windsor + 5150:

Here's a whole demo with real drums, bass etc...: of the Nation - Total Control.mp3 of the Nation - My Favourite Emotional State.mp3 of the Nation - Isolation.mp3 of the Nation - Give Me Your Name.mp3

- EMG81, I don't remember anything else
- TS808 clone
- Peavey Windsor (cheap as hell!)
- Marshall 1960 cab
- Shure SM57 & Sennheiser E606
- D&R Mic Amp

- Peavey Windsor
- Mesa Vintage PowerHouse 1000 bass cab

I didn't record these, but trust the people that did and they really like the Windsor for heavy stuff like this. Unfortunately, you can't really tell how the Windsor responds to lower gain styles etc....
Well, I got a Windsor in the mail yesterday, I really dig it so far.

Here's a few soundclips I threw together with some speaker simulation from Peavey's Revalver MKIII. I just put them in a short youtube video with a picture of the Windsor. Seems people are more inclined to check out a youtube video rather than higher-quality mp3 clips. haha.

Here's a post from another forum, I'm new to electronics so I'm trying to help explain what I'm doing to other people new to electronics as well.


I have removed C27, and C28. These are cathode resister bypass capacitors (I also removed C5 earlier), they basically let more signal pass by the cathode resistor and into the next gain stage, therefore contributing to higher gain. I definitely noticed a difference this time, the gain was lowered a bit, but it still doesn't really "clean up", still kinda gritty. Also, note that all this so far, is with the master WAY WAY down, so these changes may actually be working at practice/gig volumes. haha.

Changed R4 (1K) to a 10K.
This is the cathode resistor on the second gain stage (second half of the first 12ax7).

I think this made an "improvement" in the cleans so far, the preamp gain knob stays clean until about 12 o'clock now and the clean seems to be more natural without the 'grit' that was there previously.
After experimenting for a while, it seems the best way to add a "clean channel" is to just set it up similar to a JCM-800, and skip the first gain stage and change the cathode resister value for the second gain stage. I've got this all setup through a DPDT switch and just put it all on a RadioShack PC board earlier.


All I need now is a 3pdt switch and another pot so I can have a master volume for the clean channel...
Hi All,

I'm new here. Found this thread after doing a Google search for the Peavey Windsor. I just ordered one from GC. I thought it was a fantastic value for what you get. I ordered the half-stack. Having built a tube amp and refurbed several I figured this would be a great pro9ject amp. Like many, I want to mod it for better cleans while maintaining the ability to get dirty when necessary. I was wondering if anyone had followed through with any of the mods that can accomplish this.

I think it can probably sound very good as is, with the right tweaking of the various controls. It would be great though, to have that 100 watts of clean if one so desired. So, I've resurrected this thread in hopes of finding out if anyone has done it.

Hello, I also have a windsor head, and after much research on how to clean it up, I found only 1 blog that made sense, change preamp tube 1 & 2 to 12au7 and 12at7 respectively. I happened to have fisher amp that I was able to rob the tubes from that are at least 50 yrs old (RCA). The amp sounds great with a tube screamer in front now.
Hi there, I am relatively new to the site..just browsed into this forum. I have a clean pdf of the schematic for this amp series, if anyone interested I could send email. I was really interested in getting a windsor too. I noted in the design that the preamp section has a LOT of preamp stages and I am wondering if the low gain input jack could simply be jumpered over to the pregain pot (actually after the decouplng capacitor), effectively dropping the first stage or if there was a way to skip one stage in low gain mode. I have a an old tube amp that is an ongoing rebuild sounds very clean using only 2 stages on the preamp(using both half of 12AX7). If you are interested in modding the resistor/cap values I could post those values too.
There is more to it than number of stages. This preamp does have four stages. You should also note that between each stage is a large voltage division reducing signal level. The stages are being used for tone shaping, not simply gain.

Yes, you could jump over a stage, not sure you'd want to. But that is only my opinion.

I don't think clean was part of the design spec for this amp. I think it was intended more as a "lead" amp.
Hi Enzo, I absolutely agree with you there. The amp has had a lot of reviews about that, designed to be more of a 60 -70's ''hard rock'' amp. The Windsor series looks like it is being cleared out to make room for Peavey's new series (at more $$). Right now they are going for very low price and I am very tempted to tinker around with the circuit...
Only my opinion, but maybe the tone shaping (other than the tone stack) is great for lead, but for a clean sound I prefer to leave it as close to original signal as possible. Let you know if I pick one up.
Well, just for science, sometime plug your guitar straight into the PA system. Now you will hear what the "original signal" sounds like. Kinda thin and pale really. When I think of clean, I think of a nice Fender Twin Reverb. It is far from flat or hifi, but it sounds great and darn "clean."
Yes for sure that would be taking it to the extreme, and actually reminds me of back in the day I did try exactly that. I had a little transistor based practice amp (not enough $$ for a Fender when your a 12 year old) , but my dad had built a heathkit (from down your way!) tube based little portable PA/Stereo amp. I cobbled together a cab with some speakers and brought the thing to band practice. With a little electro-harmonix preamp (LPB-1) in between the guitar/amp to boost a bit to line level and take care of impedance...go figure.. it sounded really quite good!
Even a fender twin uses only 2 stages before the PI, with the tone stack right after the input amp stage:you are absolutely right about it sounding 'clean'...I agree when we say clean we are not talking about HiFi etc..
Hi Enzo, I did a bit of checking of what Sloan was going for. Of course you are right about the tone shaping+gain. Sloan's comparison to a JCM-800 front-end is also very accurate, the '76 version is incredibly similar. For the 'clean' input, Marshall however bypasses the input first stage V1 that the lead channel uses exclusively. The clean channel signal goes through the 470K/47pF then into the preamp volume to second stage. The lead channel hits the 1st stage V1, then through 0.022 uF then to the 470K/47pF combo. From what I remember of the JCM 800 the clean input did sound pretty 'clean'.
Also, here are my GO-TO clips for anyone asking what the Windsor sounds like:

I didn't record these, but trust the people that did and they really like the Windsor for heavy stuff like this. Unfortunately, you can't really tell how the Windsor responds to lower gain styles etc....

Old post i know but i just got one of these heads off craigslist and found this mod so i thought ide try it.

Hey Sloan did you do these mods? i did this mod last night and now im not getting any sound. Im wondering if you can check to see if maybe anything i forgot?
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